Organic and inorganic templates bearing CCo3(CO)9 cluster fragments: X-ray crystal structures of C(CH2OCOCCl3)4 and of CH3C(O)CHC(OH)MLn where MLn = CCo3(CO)9 or (C6H5)Cr(CO)3

Abstract

Pentaerythritol and trichloroacetyl chloride react to yield the tetrakis-trichloroacetate ester C(CH2-O2C-CCl3)4, 5, which crystallizes in the triclinic space group [Formula: see text] with a = 9.874(2) Å, b = 11.811(2) Å, c = 12.858(3) Å, α = 114.35(3)°, β = 95.63(3)°, γ = 99.11 (3)°, and V = 1326.5(5) Å3 for Z = 2. The molecule adopts a geometry in which the trichloroacetate chains fold to produce a flattened tetrahedron, giving a molecule of approximate D2d symmetry. Treatment of 5 with CO2(CO)8 gave, as the highest molecular weight product, the tris-cluster complex C[CH2-O2C-CCo3(CO)9]3(CH2-O2C-CCl3), 6, rather than the tetra-cluster C[CH2-O2C-CCo3(CO)9]4, 7. A space-filling model of 7, derived by replacing the CCl3 groups in 5 by CCo3(CO)9 moieties, exhibited considerable molecular crowding. Reaction of several 1,1,1-trichloroacetylacetonate salts with Co2(CO)8 gave the corresponding cluster complexes of Co(II), Co(III), or Al(III). The uncomplexed cluster ligand CH3C(O)CHC(OH)CCo3(CO)9, 9, crystallizes in the orthorhombic space group Pna21 with a = 16.226(2) Å, b = 11.6300(10) Å, c = 9.919(2) Å, V = 1871.7(4) Å3 for Z = 4. The direction of enolization of 9 has been studied by EHMO calculations. The tendency to enolize is also found in (benzoylacetone)Cr(CO)3, 17, which crystallizes in the tetragonal space group P43212 with a = 10.0840(10) Å, b = 10.0840(10) Å, c = 25.387(5) Å, V = 2581.5(6) Å3 for Z = 8. Keywords: inorganometallic clusters.